Power converters are ubiquitous in modern electronics, appliances, devices, computers, vehicles, and are an especially important part of renewable energy. A power converter is used to convert the voltage or current from a source of electricity to a voltage or current having different characteristics. For example, the power converter may convert an incoming voltage to a lower voltage, to a higher voltage, to a different voltage reference point, may converted AC to DC, DC to AC, etc. Most modern power regulators are of the “switching” type, in which a semiconductor switch periodically applies and interrupts a flow of electricity through the converter. In many such devices, the efficiency of the converter depends on the control-algorithm for operating the switch. For simplicity, conventional power converters employ a fixed switch period. The width or duty cycle of the switch operation is controlled to establish the converter characteristic.
Conventional converters perform poorly at low power because the required switch duty cycles are excessively short. To alleviate this problem, some advanced controllers use a “pulse-skipping” algorithm in which the switch period is increased in discrete multiples. Other converters operate with substantially constant switch duration and a variable switch frequency, which have efficiency problems at high power. Some conventional power converters switch between various modes of operation depending on the magnitude of the load.